Free ATPL airframe, systems and power plant 021 questions: 9 with answers
9 airframe, systems and power plant questions from the ATPL bank of ForAllPilots, with no account and no sign-up. Answer in your head, then open the answer: the right letter and its explanation are under each question. The full bank has 1,087 questions for this subject.
The 9 questions
Question 1 · 021 09 Electrics
After one time constant, a charging capacitor in an RC circuit will have reached approximately what percentage of its final voltage?
- A100%
- B37%
- C10%
- D63%
Show the answer+
Answer: D. 63%
One time constant corresponds to approximately 63.2% of the final charge/voltage value being reached.
Question 2 · 021 09 Electrics
A unit that converts electrical DC into AC is :
- Aan AC generator.
- Ba transformer rectifier unit.
- Can inverter.
- Da thermistor.
Show the answer+
Answer: C. an inverter.
A device converting DC to AC is called an inverter.
Question 3 · 021 09 Electrics
A step-down transformer has more turns on the:
- Acore, rather than either winding
- Bprimary winding than the secondary winding
- Csecondary winding than the primary winding
- Dneither winding; turns are always equal
Show the answer+
Answer: B. primary winding than the secondary winding
A step-down transformer reduces voltage, requiring more primary turns than secondary turns.
Question 4 · 021 08 Fuel system
In a compensated capacitance type quantity indicating system, the contents gauge of a half-full fuel tank indicates a fuel mass of 8000 lb. If a temperature rise increased the volume of fuel by 5 %, the indicated fuel weight would :
- Aremain the same.
- Bdecrease by 5 %.
- Cincrease by 5 %.
- Dincrease by 10 %.
Show the answer+
Answer: A. remain the same.
A compensated capacitance system corrects for changes in fuel density with temperature, so the indicated fuel mass remains essentially unchanged despite the volume increase.
Question 5 · 021 13 Oxygen systems
A pressurized aeroplane is operated at FL 300. It undergoes a rapid decompression so that the pressure in the cabin goes quickly down to the outside pressure value. What happens concerning the oxygen system ?
- Athe oxygen masks are automatically presented to cabin crew members and passengers
- Bmanual override of the automatic presentation of passenger oxygen masks is, generally speaking, not possible
- Cif the automatic mask presentation has been activated, the oxygen will flow within the first 3 minutes
- Dthe oxygen masks are automatically presented to flight crew members
Show the answer+
Answer: A. the oxygen masks are automatically presented to cabin crew members and passengers
On rapid decompression, oxygen masks are automatically released and presented to cabin crew and passengers throughout the cabin.
Question 6 · 021 07 Anti-icing and de-icing
In jet aeroplanes the 'thermal anti-ice system' is primary supplied by
- Ableed air from the engines.
- Bram air, heated via a heat exchanger.
- Cthe APU.
- Dturbo compressors.
Show the answer+
Answer: A. bleed air from the engines.
Thermal anti-ice systems on jet aeroplanes are primarily supplied with hot bleed air from the engines.
Question 7 · 021 03 Hydraulics
Discounting the possibility of leak, the level in a hydraulic reservoir will :
- Ainitially increase with system pressurisation.
- Bincrease as ambient temperature decreases.
- Calways remain the same.
- Dfluctuate with jack displacement and accumulator pressure.
Show the answer+
Answer: D. fluctuate with jack displacement and accumulator pressure.
Ignoring leaks, reservoir fluid level varies with actuator (jack) piston displacement and with the volume of fluid stored in the accumulator.
Question 8 · 021 03 Hydraulics
The hydraulic device similar to an electronic diode is a :
- Adistribution valve.
- Bshutoff valve.
- Cflow control valve.
- Dcheck valve.
Show the answer+
Answer: D. check valve.
A check valve, like an electronic diode, allows fluid flow in one direction only.
Question 9 · 021 11 Turbine engines
In a gas turbine engine, compressor blades, which are not rigidly fixed in position when the engine is stationary, take up a rigid position when the engine is running due to :
- Athe resultant of aerodynamic and centrifugal forces.
- Boil pressure.
- Cblade creep.
- Dthermal expansion.
Show the answer+
Answer: A. the resultant of aerodynamic and centrifugal forces.
Compressor blades, loosely fitted when static, are held rigidly in position when running by the combined aerodynamic and centrifugal forces acting on them.
Each answer was checked again before publication; like every explanation on the site, these may contain errors. Some explanations were rewritten for this page, sometimes with the help of an AI. Spotted a mistake? Write to us at contact@forallpilots.com.
Going further
How ForAllPilots trains you
Series of 20 or 30 questions
New questions, mistakes to review or a mix of both, with the answer and its explanation straight away.
Flashcards
Question on the front, explained answer on the back, filtered by subject, to learn without a timer.
Timed mock exam
100 questions in 150 minutes, drawn from the whole ATPL bank: a training format, not a copy of an official paper.
AI instructor, optional
From €4.99 a month on top of the Private pilot or PRO offer: it quizzes you in writing and explains your mistakes. A beta tool, it does not replace an approved instructor.
ATPL access comes with the PRO offer (which also includes Private pilot): €19.99 a month, cancel anytime, or €129 once with the Exam Pass (18 months of access, nothing renews). Prices include all taxes.